#根目录的

urls.pyurlpatterns = [    

     url(r'^admin/', admin.site.urls),  

     url(r'^book/',include('book.urls',namespace='book')),]

#应用中的

urls.pyurlpatterns = [    

url(r'^,views.index),    

url(r'^a/(?P[0-9]+),views.a_page,name='a_page'),]

index.html中

<a href="/">返回首页方法</a>

<a href="{% url 'book:a_page' a.id %}">点击</a>